"Siege" is an American comic book published by Marvel Comics from January 2010 to May 2010. It deals with the culmination of the "Dark Reign" storyline which saw Norman Osborn become the United States primary defense officer, leading H.A.M.M.E.R. and employing his own evil Avengers. The story depicted Loki manipulating Osborn into leading an all-out assault on Asgard, at the time located within the United States. Captain America and his own Avengers lead a rebellion against Osborn which escalated to an all out assault. The events in "Siege" led to Marvel Comics introducing the subsequent storyline, "Heroic Age".

The end of aftermath was described as what would be the start of a new "Heroic Age" in the Marvel Universe.[1]

The final tie-in issues of the four Avengers titles, Mighty Avengers #36, New Avengers #64, Dark Avengers #16 and Avengers: The Initiative #35 were the last ones of those series, along with a New Avengers: Finale one-shot, with art by Bryan Hitch.[3]

Though not badged as an aftermath series, a limited series starting in May 2010 examined the fall of Norman Osborn and examine the effects upon his son Harry Osborn. The series was titled Amazing Spider-Man Presents: American Son.[4]

Norman Osborn calls a meeting of the super-villainCabal, consisting of Doctor Doom, the Hood, the Taskmaster and the AsgardianGodLoki, to discuss Asgard. Asgard is the home of the Norse Gods now located floating above Broxton, Oklahoma and the last holdout in Osborn's consolidation of power. A rift develops between Doom and Osborn, creating mayhem that appears to dissolve the group. Later, under his guise of respectability, Osborn attempts in vain to secure from the President of the United States permission to invade Asgard under the claim it poses a national security threat. On Loki's advice, Osborn engineers a tragedy in which the hapless Asgardian Volstagg, manipulated into battling the super-villain team the U-Foes, inadvertently causes an explosion that kills everyone in a crowded Soldier Field football stadium in Chicago, Illinois. This gives Osborn the justification to lay siege on Asgard with military troops as well as with the Dark Avengers—his team of super-villains posing as superheroes and with loyalists planted amid the various "50-State Initiative" teams of heroes. Osborn's aide-de-camp, Victoria Hand, growing worried over Osborn's instability, suggests unsuccessfully that Osborn seek therapy. Shortly afterward, the President realizes likewise and orders Hand to produce Osborn.

In the meantime, in order to better control the highly powerful but psychologically fragile superhero the Sentry, who has allowed himself to be under Osborn's care, Osborn has the villainous Bullseye kill the Sentry's wife, Lindy Reynolds. He then claimed that she had committed suicide. Concurrently, Loki prepares Asgard for invasion through selective assassination and by neutralizing Heimdall, the city's guardian.

The siege begins with the Sentry attacking Asgard, followed by a massive aerial assault led by Osborn in his Iron Patriot armor. The Asgardian Thunder-God Thor, who has been banished from Asgard for some time, is stunned and falls in battle. With the attack on Asgard instantly becoming a major news story, Steve Rogers, the erstwhile Captain America, assembles a group of legitimate Avengers in Brooklyn, New York City, to battle the Dark Avengers, help defend Asgard and aid their comrade Thor. At the same time the Avengers resistance led by Tigra, Justice, and Gauntlet launch their own attack on Camp H.A.M.M.E.R., aimed at eliminating Osborn's Initiative.

Osborn's people offer Todd Keller, a conservative talk show host, exclusive official coverage of the siege, in order to mould public opinion. Meanwhile, longtime investigative journalist Ben Urich, editor of the New York City newspaper The Front Line, heads to the Oklahoma battle site with cameraman Will Stern. Volstagg, whom they meet in a chance encounter along the way, accompanies them and gives the reporters his own perspective.

As the battle in Asgard intensifies, the Olympian warrior Ares, whom Osborn had deceptively recruited to his Dark Avengers, realizes the truth about Osborn and vows to kill him. Osborn has the Sentry brutally kill Ares instead. Osborn declares martial law just as Rogers and a contingent of Avengers arrives.[5][6] Volstagg, with the aid of a local sheriff who is suspicions about Osborn have been raised, speaks to the public from a webcam video, leading to the beginning of public disenchantment with the increasingly volatile Osborn.

The siege continues with the super-villain Scourge using the enchanted spear of Asgard's ruler, Odin, to sever the left limbs of the superhero U.S. Agent.[7] The conflicted hero Night Thrasher who had been compelled to make a Faustian bargain with Osborn, turns on Osborn by battling Osborn's Cabal minion the Hood.[8] In Washington, the President orders the Secretary of State to dispatch military forces to Oklahoma to have Osborn and the Dark Avengers arrested for treason. At that moment in Asgard, Osborn is struck down by Captain America's shield,[9][10] yet manages to order the Sentry to destroy the infrastructure of Asgard. Sentry, having survived a flurry of brutal blows from Thor unscathed and on the verge of tearing Thor apart, transforms into the evil Void (which greatly multiplies his power to evolved heights) and leaves Thor. He then annihilates Asgard bringing it crashing down to Earth.[9][11] Rogers finds Osborn in the wreckage and places him under arrest. Before anyone can react further, Osborn's armor, now under the control of its original inventor, Tony Stark explodes off his body on live television, revealing his face painted in the image of the Green Goblin. He begins raving that with himself now being powerless, he no longer has the leverage to control the Sentry, who is now fully possessed by his nihilistic other self, the Void, which Osborn is convinced is the Angel of Death.[9]

As the Void battles the Avengers, Loki repents and begs Odin to let him use the mystical Norn Stones to power-boost the heroes and give them the strength to win the day. The Void, realizing that the heroes' enhanced power is being granted to them by Loki, kills Loki. Spurred on by Loki's sacrifice, Thor and the others battle the Void to a point that it reverts to the Sentry's human form. The Sentry begs the heroes to kill him, and Thor regretfully complies, striking the Sentry down with a lightning blast that leaves only a charred skeleton.[12] As Thor takes the Sentry's body to the sun, the New Avengers round up the Dark Avengers. Victoria Hand, the renegade members of the Initiative and the remaining members of the Cabal and others are placed under arrest. Rogers gives his former partner, Bucky Barnes, his Captain America shield, bequeathing Barnes the mantle.[13]

As the Avengers and their allies celebrate their victory at Stark Tower, the Superhuman Registration Act is abolished and Thor and his fellow Asgardian warriors offer an alliance with Earth, creating a portal to Asgard atop Stark Tower. The President asks Rogers to take over Osborn's position.[12][14] A large group of heroes later attend the Sentry's memorial service.[15] Rogers says he will continue the 50 State Initiative and reform the original Avengers group with Bucky (as Captain America), Stark and Thor as its main members.[16] He also assigns Victoria Hand to work with the New Avengers.[13]U.S. Agent is made warden of the maximum security super-villain prison The Raft.[17]

In the special "What if..." series, the story "What if Osborn won the Siege of Asgard" is told. Ares gives in to his intuition before the Siege of Asgard, attacking Osborn in his own office after realizing Osborn lied to him. Sentry murders Ares on the spot allowing him to rest up between battles and allowing him to head into battle fully powered. In turn, this leads to him being able to kill Thor as well as Captain America. Most of the heroes present are subsequently slaughtered by the Dark Avengers. Doom has himself and Emma Frost teleported out of the battle and comes up with a new strategy. New strategy have Emma scan the Dark Avengers and find out the truth about Lindy's death. Bullseye is found out, and Emma shows Sentry the truth of what happens, with catastrophic results. Sentry's fragile psyche is shattered entirely and he goes on a murderous rampage, killing both Frost and Bullseye, before transforming into a fully powered Void, who then kills Doom, Taskmaster and the Hood. He then confronts Osborn and thanks him for releasing him, only to kill him too. In the end, with the Avengers, Dark Avengers, and the Gods all defeated, none are left to fight the Void and he eventually consumes Earth entirely, before spreading out to the rest of the universe.